EV charging in an Indian apartment comes with its own vocabulary, and most of it is simpler than it sounds. Your DISCOM is the company that sends your electricity bill. Sanctioned load is the maximum power your flat may draw. A kWh — a "unit" on your bill — is a quantity of energy, while a kW is how fast that energy flows. An RCCB is a safety switch that cuts power when current leaks. This glossary explains more than twenty such terms in plain language, grouped into supply, charging, safety and society topics, so you can read an installer's quotation or sit through an RWA meeting without getting lost.
Electricity supply terms on your bill and DISCOM paperwork
DISCOM
Short for distribution company — the organisation that supplies electricity to your building and bills you for it. Questions about meters, new connections, extra load and tariffs all end up with your DISCOM, so note which one serves your society.
Unit (kWh)
The word your bill uses for one kilowatt-hour of energy. If the bill shows 250 units, you consumed 250 kWh. EV charging is measured in the same units as everything else in your flat — there is no separate "EV unit".
Tariff slab
Many residential tariffs charge a lower rate for the first block of monthly units and higher rates for the blocks after it. Home charging adds units and can push you into a higher slab, so read the slab structure printed on your own bill.
Sanctioned load
The maximum power, in kilowatts, your connection is approved to draw — it is printed on your bill. A charger draws steadily for hours, so compare its rating with your sanctioned load early; our apartment EV readiness checklist walks you through this and seven other checks.
Load enhancement
The formal request to your DISCOM to raise your sanctioned load. Procedures and charges differ between DISCOMs and change over time, so confirm the current process with yours before assuming you need it.
LT connection
A low-tension connection — the ordinary supply that individual homes receive, as opposed to the high-tension bulk supply some large complexes take. Most flat meters are LT; how your society's common areas are supplied may differ, and the committee will know.
Charging basics: kW, kWh, AC, DC and plugs
kW versus kWh
A kilowatt (kW) is speed; a kilowatt-hour (kWh) is quantity. A 3 kW charger running for one hour delivers about 3 kWh. As an illustration only: refilling 15 kWh at, say, ₹8 per unit (check your own bill) would cost around ₹120.
AC and DC charging
Your building supplies alternating current; the battery stores direct current. AC charging sends mains power to the car, which converts it internally — slower, but simple and affordable to install. DC fast charging converts power in a large external unit — quick, costly, and rarely practical for private apartment parking.
Onboard charger
The converter inside your vehicle that turns AC into DC for the battery. Its rating caps your AC charging speed: a car with a 3.3 kW onboard charger will not charge any faster from a bigger wall box.
Type 2 connector
A plug design widely used for AC charging on electric cars in India. Connectors vary by model, so let your car's manual or dealer confirm what yours uses before you buy any charger or cable.
Granny charger
The informal name for the portable charging cable bundled with many EVs, which plugs into an ordinary heavy-duty socket. Handy, but it works the socket and wiring hard for hours — have an electrician verify the circuit, and never run it through household extension boards.
Wall box
A fixed AC charger mounted near your parking spot on its own protected circuit, commonly sold in ratings such as 3.3 kW and 7.2 kW. Our 3.3 kW versus 7.2 kW comparison explains which size actually suits apartment use.
Safety and protection terms your electrician will use
Dedicated circuit
A cable run that serves only the charger, with its own protective devices, instead of sharing a circuit with other appliances. Most careful installers treat this as non-negotiable for a fixed charging point.
MCB
Miniature circuit breaker — a switch that trips when a circuit draws too much current, protecting the wiring from overheating. It guards the cable, not the person; shock protection is the RCCB's job.
RCCB
Residual current circuit breaker — a device that trips almost instantly when current leaks out of a circuit, for instance through a person or damp equipment. It is the key shock-protection device for charging points in parking areas.
RCBO
A single device that combines the MCB's overload protection with the RCCB's leakage protection. Installers often fit one RCBO per charging point; the exact type and rating is your electrician's call.
Earthing
The connection that gives fault current a safe path into the ground so protective devices can trip. Weak earthing is a common finding in older parking areas — ask for it to be tested, not assumed, and see our apartment EV charging safety checklist for what else to verify.
IP rating
A code describing how well an enclosure keeps out dust and water. Equipment in open stilt parking or near wash areas needs a suitably weather-resistant rating — ask your installer what they propose and why.
Society, permission and billing terms
RWA and managing committee
The resident welfare association, or the housing society's elected managing committee — the body that controls common areas and can permit work in them. Your first charger conversation usually happens here.
NOC
No-objection certificate — a written note recording that the society does not object to your installation, usually with conditions such as using a licensed electrician and paying for your own units. Our guide on requesting charger permission from your RWA shows how to ask, and you can start from the permission request letter template.
Common area
Space owned collectively by all members — driveways, stilt parking, walls, ducts and often the parking slots themselves, depending on how they were allotted. Cables crossing common area are the main reason society permission matters even for a fully private charger.
Bye-laws
The registered rules your society operates under, which shape what the committee may approve and how decisions are taken. They differ from society to society, so read your own copy rather than relying on what another building did.
Sub-meter
A small additional meter on the charger's circuit that records exactly how many units your charging used, so the society can bill you at an agreed rate. We compare it with app-based billing in sub-meter versus smart-charger billing.
Smart charger and load management
A smart charger measures its own consumption and reports it through an app. Load management is software that shares limited capacity among several chargers so they never overload the building's supply together — useful once a society moves to shared charging points.
Who to ask: a quick reference
When a term comes up mid-discussion, what matters is not memorising it but knowing whose desk it belongs to. This table sorts the glossary by the person to approach first.
| Your question is about | Terms involved | Ask first |
|---|---|---|
| Your connection, tariff or extra load | DISCOM, unit, tariff slab, sanctioned load, load enhancement, LT connection | Your DISCOM's customer care or local office |
| Wiring, protection and installation safety | Dedicated circuit, MCB, RCCB, RCBO, earthing, IP rating | A licensed electrician or professional installer |
| Permission and use of shared spaces | RWA, NOC, common area, bye-laws | Your managing committee or RWA office |
| Paying fairly for the units you charge | Sub-meter, smart charger, load management | The committee, alongside your electrician |
Common questions
What is the difference between kW and kWh in one line?
kW is speed and kWh is quantity: a 3 kW charger running for two hours delivers about 6 kWh, which appears on your bill as 6 units. Charger ratings are quoted in kW; battery sizes and electricity bills are in kWh.
Do I need to know all these terms before approaching my RWA?
No. Four cover most conversations: sanctioned load (can your supply handle it), NOC (the permission itself), common area (why permission is needed) and sub-meter (how you will pay). The rest you can leave to your electrician and look up here when they appear.
Is a granny charger enough, or do I need a wall box?
For modest daily running, a granny charger on an electrician-verified socket can be a workable start. A wall box on a dedicated, properly protected circuit is the safer and more convenient long-term arrangement, especially where the cable route passes through common areas.
Is an NOC a legal approval?
Treat it as a record of your society's consent, not a statutory clearance. It does not replace electrical safety checks, and it does not cover anything your DISCOM may separately require for the connection — confirm that side directly with them.
A glossary makes you conversational, not qualified. Before any wiring is planned or a single cable is run, have a licensed electrician survey your parking and meter room, and confirm current procedures, tariffs and load requirements directly with your DISCOM — both will use these very terms, and now you can follow along.